Apparatus and method of encoding 3d image

ABSTRACT

Disclosed is a three-dimensional (3D) image encoding apparatus. The 3D image encoding apparatus includes a first compressed information generation unit to generate first compressed information used to encode one image of two types of images to form a 3D image and a second compressed information generation unit to generate second compressed information used to encode another one image using the first compressed information.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of Korean PatentApplication No. 10-2010-0043812, filed on May 11, 2010, in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference.

BACKGROUND

1. Field

One or more embodiments relate to an apparatus and method of encoding athree-dimensional (3D) image, and more particularly, to an apparatus andmethod of encoding one image using compressed information of another oneimage of two images to form a 3D image.

2. Description of the Related Art

A stereoscopic image is a three-dimensional (3D) image which providesvisual information about depth and space at the same time. Here, unlikestereoscopy that presents a different viewpoint image to each eye, inorder to provide an image as perceived from a different aspect whenevera viewpoint of a viewer changes, an image taken from a differentviewpoint is needed. Applications using an image taken from a differentaspect include a free-viewpoint TV scheme, a 3D TV scheme, etc. Afree-viewpoint TV scheme allows a user to optionally change a viewpointon an object by acquiring multi-viewpoint images of the same scene andanalyzing the images. A 3D TV presents a different image to each eye,allowing a viewer to perceive virtual 3D depth. However, an image takenfrom different viewpoints includes a massive amount of data, and thus itis difficult to secure a network infrastructure and a ground-wavebandwidth when compressing and transmitting the image.

Instead of compressing and transmitting all images from differentviewpoints, a depth image is generated and compressively transmittedalong with images from part of the viewpoints, thereby reducing anamount of data to be compressed. A depth image is an image to representa distance between a viewer and an object in a color image as a value of0 to 255, and thus characteristics thereof are similar to those of acolor image.

SUMMARY

According to an aspect of one or more embodiments, there may be provideda three-dimensional (3D) image encoding apparatus, the apparatusincluding a first encoder to generate first compressed information in afirst image macroblock (MB) which is one of images to form a 3D image,and to encode the first image MB using the first compressed information;and a second encoder to generate second compressed information using thefirst compressed information, and to encode a second image MB which isanother one of the images to form the 3D image using the secondcompressed information.

Here, the first image MB may be one of a color image MB and a depthimage MB, and the second image MB may be another one of the color imageMB and the depth image MB which is different from the first image MB.

Here, the first compressed information may be a first image intraprediction mode (IPM) which represents an IPM of the first image MB, andthe second compressed information may be a second image IPM to representan IPM of the second image MB.

Here, the first encoder may include a first image intra prediction unitto respectively generate prediction blocks according to IPMs, and afirst image IPM determination unit to examine a compression efficiencyby differentiating the first image MB by the prediction blocks andrate-distortion optimizing a differentiation result and to determine anIPM having superior or relatively high compression efficiency among theIPMs as the first image IPM.

Here, the second encoder may include a second image IPM determinationunit to determine the first image IPM as the second image IPM that isthe IPM of the second image MB.

Here, the second encoder may include a candidate IPM generation unit togenerate candidate IPMs using the first image IPM; a second image intraprediction unit to respectively generate candidate prediction blocksaccording to the candidate IPMs; and a second image IPM determinationunit to examine a compression efficiency by differentiating the secondimage MB by the candidate prediction blocks and rate-distortionoptimizing a differentiation result, and to determine a candidate IPMhaving superior compression efficiency among the candidate IPMs as thesecond image IPM.

Here, the first compressed information may be a first image motionvector (MV) to represent an MV of the first image MB, and the secondcompressed information may be a second image MV to represent an MV ofthe second image MB.

Here, the first encoder may include a first image predictive MV (PMV)calculation unit to calculate a first image PMV which represents a PMVof the first image MB using the first image MB and adjacent blocks; anda first image motion explorer to generate the first image MV that is afinal MV of the first image MB by motion exploration in a first imagebased on the first image PMV.

Here, the second encoder may include a second image MV determinationunit to determine the first image MV as the second image MV that is afinal MV of the second image MB.

Here, the second encoder may include a second image motion explorer togenerate the second image MV that is a final MV of the second image MBby motion exploration in a second image based on the first image MV.

Here, the second encoder may include a second image first motionexplorer to generate a second image first MV which is one of candidateMVs of the second image MB by motion exploration in a second image basedon the first image MV; a second image PMV calculation unit to calculatea second image PMV which represents a PMV of the second image MB usingthe second image MB block and adjacent blocks; a motion explorer togenerate a second image second MV which is one of the candidate MVs ofthe second image MB by motion exploration in the second image based onthe second image PMV; and a second image MV selection unit to select anMV having a minimum or relatively low motion cost function as the secondimage MV by comparing the second image first MV with the second imagesecond MV.

According to an aspect of one or more embodiments, there may be provideda 3D image decoding apparatus, the apparatus including a first decoderto decode an encoded first image MB using first compressed informationwhen receiving the encoded first image MB which is one of images to forma 3D image and the first compressed information; and a second decoder togenerate second compressed information using the first compressedinformation and to decode an encoded second image MB using the secondcompressed information when receiving the encoded second image MB whichis another one of the images to form the 3D image.

Here, the first image MB may be one of a color image MB and a depthimage MB, and the second image MB may be another one of the color imageMB and the depth image MB which is different from the first image MB.

Here, the first compressed information may be a first image IPM torepresent an IPM of the first image MB, and the second compressedinformation may be a second image IPM to represent an IPM of the secondimage MB.

Here, the first decoder may receive the first image IPM along with theencoded first image MB and decode the encoded first image MB using thefirst image IPM.

Here, the second decoder may receive the encoded second image MB anddecode the encoded second image MB using the first image IPM.

Here, the second decoder may receive an index bit along with the encodedsecond image MB, generate candidate IPMs using the first image IPM, anddecode the encoded second image MB using a candidate IPM correspondingto the index bit among the candidate IPMs as the second image IPM.

Here, the first compressed information may be a first image MV whichrepresents an MV of the first image MB, and the second compressedinformation may be a second image MV which represents an MV of thesecond image MB.

Here, the first decoder may receive the first image MV along with theencoded first image MB and decode the encoded first image MB using thefirst image MV.

Here, the second decoder may receive the encoded second image MB anddecode the encoded second image MB using the first image MV.

Here, the second decoder may receive the encoded second image MB,reconstruct the second image MV using the first image MV as a secondimage PMV, and decode the encoded second image MB using the second imageMV.

Here, the second decoder may receive the encoded second image MB and anindex bit; and the second decoder may reconstruct the second image MVusing the first image MV as a second image PMV and decode the encodedsecond image MB using the second image MV when either the index bitindicates the first image MV is the second image PMV, or the seconddecoder may decode the encoded second image MB using the second image MVreceived along with the encoded second image MB when the index bitindicates that the second PMV is calculated through the second image MB.

According to an aspect of one or more embodiments, there may be provideda 3D image encoding method, the method including generating firstcompressed information in a first image MB which is one of images toform a 3D image and encoding the first image MB using the firstcompressed information; and generating second compressed informationusing the first compressed information and encoding a second image MBwhich is another one of the images to form the 3D image using the secondcompressed information.

Here, the first image MB may be one of a color image MB and a depthimage MB, and the second image MB may be another one of the color imageMB and the depth image which is different from the first image MB.

Here, the first compressed information may be a first image IPM torepresent an IPM of the first image MB, and the second compressedinformation may be a second image IPM to represent an IPM of the secondimage MB.

Here, the generating of the first compressed information may includerespectively generating prediction blocks according to IPMs; examining acompression efficiency by differentiating the first image MB by theprediction blocks and rate-distortion optimizing the first image MB; anddetermining an IPM having superior or relatively high compressionefficiency among the IPMs as the first image IPM.

Here, the generating of the second compressed information may includedetermining the first image IPM as the second image IPM that is an IPMof the second image MB.

Here, the generating of the second compressed information may includegenerating candidate IPMs using the first image IPM; respectivelygenerating candidate prediction blocks according to the candidate IPMs;examining a compression efficiency by differentiating the second imageMB by the candidate prediction blocks and rate-distortion optimizing thesecond image MB; and determining a candidate IPM having superior orrelatively high compression efficiency among the candidate IPMs as thesecond image IPM.

Here, the first compressed information may be a first image MV whichrepresents an MV of the first image MB, and the second compressedinformation may be a second image MV which represents an MV of thesecond image MB.

Here, the generating of the first image PMV that is the first compressedinformation may include calculating the first image PMV which representsa PMV of the first image MB using the first image MB and adjacentblocks, and generating the first image MV that is a final MV of thefirst image MB by motion exploration of a first image.

Here, the generating of the second image PMV that is the secondcompressed information may include determining the first image MV as thesecond image MV that is a final MV of the second image MB.

Here, the generating of the second image PMV that is the secondcompressed information may include generating the second image MV thatis a final MV of the second image MB by motion exploration of a secondimage based on the first image MV.

Here, the generating of the second image PMV that is the secondcompressed information may include generating a second image first MVwhich is one of candidate MVs of the second image MB by motionexploration of a second image based on the first image MV; calculating asecond image PMV which represents a PMV of the second image MB using thesecond image MB and adjacent blocks; generating a second image second MVwhich is one of the candidate MVs of the second image MB by motionexploration of the second image based on the second PMV; and selectingan MV having a minimum or relatively low motion cost function as thesecond image MV by comparing the second image first MV and the secondimage second MV.

According to an aspect of one or more embodiments, there may be provideda 3D image decoding method, the method including receiving an encodedfirst image MB which is one of images to form a 3D image and a firstcompressed information; decoding the encoded first image MB using thefirst compressed image; receiving an encoded second image MB which isanother one of the images to form the 3D image; generating secondcompressed information using the first compressed information; anddecoding the encoded second image MB using the second compressedinformation.

Additional aspects of embodiments will be set forth in part in thedescription which follows and, in part, will be apparent from thedescription, or may be learned by practice of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of embodiments, taken inconjunction with the accompanying drawings of which:

FIG. 1 illustrates an example of a system of encoding and decoding a 3Dimage according to example embodiments;

FIG. 2 illustrates an example of an apparatus of generating an intraprediction mode of a color image and a depth image;

FIG. 3 illustrates another example of the apparatus of generating theintra prediction mode of the color image and the depth image;

FIG. 4 illustrates four modes of an intra 16×16 mode according toexample embodiments;

FIG. 5 illustrates nine modes of an intra 4×4 mode according to exampleembodiments;

FIG. 6 illustrates an example of an apparatus of generating a motionvector of a color image and a depth image;

FIG. 7 illustrates another example of the apparatus of generating themotion vector of the color image and the depth image;

FIG. 8 illustrates still another example of the apparatus of generatingthe motion vector of the color image and the depth image;

FIG. 9 is a flowchart illustrating a process of encoding a 3D imageaccording to example embodiments;

FIG. 10 is a flowchart illustrating a process of generating an intraprediction mode of a color image or a depth image according to exampleembodiments;

FIG. 11 is a flowchart illustrating an example of generating an intraprediction mode of an image using an intra prediction mode of anotherimage according to example embodiments;

FIG. 12 is a flowchart illustrating another example of generating anintra prediction mode of an image using an intra prediction mode ofanother image according to example embodiments;

FIG. 13 is a flowchart illustrating a process of generating a motionvector of a color image or a depth image according to exampleembodiments;

FIG. 14 is a flowchart illustrating an example of generating a motionvector of an image using a motion vector of another image according toexample embodiments;

FIG. 15 is a flowchart illustrating another example of generating amotion vector of an image using a motion vector of another imageaccording to example embodiments; and

FIG. 16 is a flowchart illustrating still another example of generatinga motion vector of an image using a motion vector of another imageaccording to example embodiments.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to the like elements throughout. Embodiments aredescribed below to explain the present disclosure by referring to thefigures.

FIG. 1 illustrates an example of a system of encoding and decoding a 3Dimage according to an embodiment.

Referring to FIG. 1, a 3D image system may include a 3D image encodingapparatus 100 to encode a 3D image formed of a color image and a depthimage and a 3D image decoding apparatus 150 to decode an encoded 3Dimage.

The 3D image encoding apparatus 100 may include a first encoder 110 anda second encoder 120.

The first encoder 110 may include a first compressed informationgeneration unit 112 to generate first compressed information in a firstimage macroblock (MB) which is one of images to form a 3D image, andencodes the first image MB using the first compressed information. Here,the first image MB may be one of a color image MB and a depth image MB.The first compressed information may be a first image intra predictionmode (IPM) to represent an IMP of the first image MB, or a first imagemotion vector (MV) to represent an MB of the first image MB.

The second encoder 120 may include a second compressed informationgeneration unit 122 to generate second compressed information using thefirst compressed information, and encodes a second image MB which isanother one of the images to form the 3D image using the secondcompressed information. Here, the second image MB is another one of thecolor image MB and the depth image MB which is different from the firstimage MB. The second compressed information may be a second image IPM torepresent an IMP of the second image MB or a second image MV torepresent an MV of the second image MB.

The 3D image decoding apparatus 150 may include a first decoder 160 anda second decoder 170.

The first decoder 160 receives an encoded first image MB, identifiesfirst compressed information in the encoded first image MB, and decodesthe encoded first image MB using the first compressed information.

The second decoder 170 receives an encoded second image MB, generatessecond compressed information using the first compressed informationreceived from the first decoder 160, and decodes the encoded secondimage MB using the second compressed information.

When the compressed information is an IPM, a configuration of the firstcompressed information generation unit 112 and the second compressedinformation generation unit 122 which generate an IPM are describedbelow with reference to FIGS. 2 and 3.

FIG. 2 illustrates an example of an apparatus of generating an IPM of acolor image and a depth image.

Referring to FIG. 2, the first compressed information generation unit112 includes a first image intra prediction unit 210 and a first imageIPM determination unit 220, and the second compressed informationgeneration unit 122 includes a second image IPM determination unit 230.

The first image intra prediction unit 210 generates predication blocksfrom boundary pixels of the first image MB according to IPMs,respectively. Here, when the first image MB is 16×16, four IPMs may beused, as shown in FIG. 4. When the first image MB is 4×4, nine IPMs maybe used, as shown in FIG. 5.

FIG. 4 illustrates four modes of an intra 16×16 mode according toexample embodiments.

Referring to FIG. 4, the four modes of the intra 16×16 mode may includea mode 0 400 to a mode 3 430.

The mode 0 (vertical mode) 400 generates a prediction block verticallyusing an upper boundary pixel. The mode 1 (horizontal mode) 410generates a prediction pixel horizontally using a left boundary pixel togenerate a prediction block. The mode 2 (DC mode) 420 generates aprediction block using a mean of the upper boundary pixel and the leftboundary pixel. The mode 3 (plane mode) 430 generates a prediction blockbased on the upper boundary pixel and the left boundary pixel.

FIG. 5 illustrates nine modes of an intra 4×4 mode according to exampleembodiments.

Referring to FIG. 5, the nine modes of the infra 4×4 mode may include amode 0 500 to a mode 8 580. As shown in FIG. 5, the mode 0 500 generatesprediction blocks vertically using upper boundary pixels A, B, C, and D.A mode 1 510 generates prediction blocks horizontally using leftboundary pixels I, J, K, and L. A mode 2 520 generates prediction blocksusing respective means of the upper boundary pixels A, B, C, and D andthe left boundary pixels I, J, K, and L. A mode 3 530 generatesprediction blocks by interpolation of boundary pixels at 45 degrees froma right upper end to a lower left end. A mode 4 540 generates predictionblocks by expansion of boundary blocks at 45 degrees to a lower rightend. A mode 5 550 generates prediction blocks by expansion of boundaryblocks at about 26.6 degrees to a right of a vertical line. A mode 6 560generates prediction blocks by expansion of boundary pixels at about26.6 degrees to a lower direction of a horizontal line. A mode 7 570generates prediction blocks by expansion of boundary pixels at about26.6 degrees to a left of the vertical line. The mode 8 580 generatesprediction blocks by interpolation of boundary pixels at about 26.6degrees to an upper direction of the horizontal line.

The first image IPM determination unit 220 differentiates the firstimage MB by the prediction blocks and rate-distortion optimizes adifferentiation result to examine a compression efficiency, anddetermines an IPM having relatively high compression efficiency amongthe IPMs as a first image IPM.

The second image IPM determination unit 230 determines the first imageIPM as a second image IPM.

As shown in FIG. 2, when the second compressed information generationunit 122 determines the first image IPM as the second image IPM, thefirst encoder 110 transmits the first image IPM together with an encodedfirst image MB to the first decoder 160 (shown in FIG. 1).

The first decoder 160 of the 3D image decoding apparatus 150 decodes anencoded first image MB using the first image IPM and provides the firstimage IPM to the second decoder 170. The second decoder 170 receives anencoded second image MB from the second encoder 120 and decodes theencoded second image MB using the first image IPM provided from thefirst decoder 160.

Thus, the second encoder 120 may not need to transmit the second imageIPM when transmitting the encoded second image MB.

FIG. 3 illustrates another example of the apparatus of generating theIPM of the color image and the depth image.

Referring to FIG. 3, the first compressed information generation unit112 may include the first image intra prediction unit 210 and the firstimage IPM determination unit 220. The second compressed informationgeneration unit 122 may include a candidate IPM generation unit 310, asecond image intra prediction unit 320, and a second image IPMdetermination unit 330.

The candidate IPM generation unit 310 generates candidate IPMs using afirst image IPM received from the first image IPM determination unit220. The candidate IPMs are generated by tilting the first image IPM ata preset angle to either the right or left. Here, a weighted value ofboundary pixels of adjacent blocks may vary based on the preset angle.

The second image intra prediction unit 320 generates candidateprediction blocks according to the candidate IPMs, respectively.

The second image IPM determination unit 330 differentiates the secondimage MB by the candidate prediction blocks and, rate-distortionoptimizes a differentiation result to examine a compression efficiency,and determines a candidate IPM having relatively high compressionefficiency among the candidate IPMs as a second image IPM.

A configuration of the first compressed information generation unit 112and the second compressed information generation unit 122 to generate anMV, when the compressed information is an MV, is described below withreference to FIGS. 6 to 8.

As shown in FIG. 1 and FIG. 3, when the second compressed informationgeneration unit 122 generates the candidate IPMs using the first imageIPM and determines the second image IPM among the candidate IPMs, thefirst encoder 110 transmits the first image IPM along with the firstimage MB to the first decoder 160. Then, the second encoder 120transmits an index bit to represent the second image IPM along with theencoded second image MB to the second decoder 170.

The first decoder 160 of the 3D image decoding apparatus 150 decodes theencoded first image MB using the first image IPM and provides the firstimage IPM to the second decoder 170. The second decoder 170 receives theencoded second image MB and the index bit from the second encoder 120.The second decoder 170 generates candidate IPMs using the first imageIPM provided from the first decoder 160 and identifies a candidate IPMcorresponding to the index bit among the candidate IPMs as the secondimage IPM. Then, the second decoder 170 decodes the encoded second imageMB using the identified second image IPM.

FIG. 6 illustrates an example of an apparatus of generating an MV of acolor image and a depth image.

Referring to FIG. 6, the first compressed information generation unit112 includes a first image predictive motion vector (PMV) calculationunit 610 and a first image motion explorer 620, and the secondcompressed information generation unit 122 includes a second image MVdetermination unit 630.

The first image PMV calculation unit 610 calculates a first image PMVrepresenting a PMV of the first image MB using the first image MB andadjacent blocks. For example, the first image PMV calculation unit 610may calculate the first image PMV into a vector obtained by medianfilters of MVs of left, upper, and right-upper blocks that are the firstimage MB and the adjacent blocks in horizontal/vertical directions,respectively.

The first image motion explorer 620 explores motion in a first imagebased on the first image PMV to generate a first image MV that is afinal MV of the first image MB.

The second image MV determination unit 630 determines the first image MVas a second image MV.

As shown in FIG. 6, when the second compressed information generationunit 122 determines the first image MV is the second image MV, the firstencoder 110 transmits the first image MV along with the encoded firstimage MB.

The first decoder 160 of the 3D image decoding apparatus 150 decodes theencoded first image MB using the first image MV and provides the firstimage MV to the second decoder 170. The second decoder 170 receives theencoded second image MB from the second encoder 120 and decodes theencoded second image MB using the first image MV provided from the firstdecoder 160.

Thus, the second encoder 120 may not need to transmit the second imageMV when transmitting the encoded second image MB.

FIG. 7 illustrates another example of the apparatus of generating the MVof the color image and the depth image.

Referring to FIG. 7, the first compressed information generation unit112 includes the first image PMV calculation unit 610 and the firstimage motion explorer 620, and the second compressed informationgeneration unit 122 includes a second image PMV determination unit 710and a second image motion explorer 720.

The second image PMV determination unit 710 determines the first imageMV as a second image PMV representing a PMV of the second image MB.

The second image motion explorer 720 explores motion in a second imagebased on the second image PMV determined by the second image PMVdetermination unit 710 to generate a second image MV that is a final MVof the second image MB.

As shown in FIG. 7, when the second compressed information generationunit 122 determines the first image MV is the second image PMV anddetermines the second image MV by motion exploration in the secondimage, the first encoder 110 transmits the first image MV along with theencoded first image MB.

The first decoder 160 of the 3D image decoding apparatus 150 decodes theencoded first image MB using the first image MV and provides the firstimage MV to the second decoder 170. The second decoder 170 receives theencoded second image MB from the second encoder 120. The second decoder170 generates the second image PMV using the first image MV providedfrom the first decoder 60 and reconstructs the second image MV using thesecond image PMV. Then, the second decoder 170 decodes the encodedsecond image MB using the second image MV.

FIG. 8 illustrates still another example of the apparatus of generatingthe motion vector of the color image and the depth image.

Referring to FIG. 8, the first compressed information generation unit112 includes the first image PMV calculation unit 610 and the firstimage motion explorer 620. The second compressed information generationunit 122 includes the second image PMV determination unit 710, a secondimage first motion explorer 805, a second image PMV calculation unit810, a second image second motion explorer 820, and a second image MVselection unit 830.

The second image PMV determination unit 710 determines the first imageMV as the second image PMV representing the PMV of the second image MB.

The second image first motion explorer 805 explores motion in the secondimage based on the second image PMV determined by the second image PMVdetermination unit 710 to generate a second image first MV that is acandidate MV of the second image MB.

The second image PMV calculation unit 810 calculates the second imagePMV representing the PMV of the second image MB using the second imageMB and adjacent blocks. For example, the second image PMV calculationunit 810 may calculate the second image PMV into a vector obtained bymedian filter of MVs of left, upper, and upper-right blocks that are thesecond image MB and the adjacent blocks in horizontal/verticaldirections, respectively.

The second image second motion explorer 820 explores motion in thesecond image based on the second image PMV calculated by the secondimage PMV calculation unit 810 to generate a second image second MV thatis a candidate MV of the second image MB.

The second image MV selection unit 830 compares the second image firstMV with the second image second MV and selects an MV having a minimum(or relatively low) motion cost function as the second image MV.

As shown in FIG. 8, when the second compressed information generationunit 122 generates the second image MV and a general scheme or theprocess as described with reference to FIG. 7 is used, the first encoder110 transmits the first image MV along with the encoded first image MB.

The second encoder 120 transmits an index bit along with the encodedsecond image MB. Here, the index bit is information indicating which ofa general scheme and the process as described with reference to FIG. 7the second image MV is generated by.

When the index bit indicates the second image PMV is calculated throughthe second image MB, that is, the second image MV is generated by ageneral scheme, the second decoder 170 transmits the index bit and thesecond image MV along with the second image MB.

The first decoder 160 of the 3D image decoding apparatus 150 decodes theencoded first image MB using the first image MV and provides the firstimage MV to the second decoder 170.

The second decoder 170 may receive the encoded second image MB and theindex bit from the second encoder 120 and further receive the secondimage MV.

When the index bit indicates that the first image MV is the second imagePMV, the second decoder 170 generates the second image PMV using thefirst image MV provided from the first decoder 160 and reconstructs thesecond image MV using the second image PMV. Then, the second decoder 170decodes the encoded second image MB using the second image MV.

However, when the index bit indicates that the second image PMV iscalculated through the second image MB, the second decoder 170 decodesthe encoded second image MB using the second image MV received alongwith the encoded second image MB from the second encoder 120.

Hereinafter, a process of encoding a 3D image with the aboveconfiguration according to an embodiment is described below withreference to drawings.

FIG. 9 is a flowchart illustrating a process of encoding a 3D imageaccording to example embodiments.

Referring to FIG. 9, when the 3D image encoding apparatus 100 receives afirst image MB and a second image MB which form a 3D image in operation910, the 3D image encoding apparatus 100 generates first compressedinformation in the first image MB in operation 912. Here, the firstimage MB may be one of a color image MB and a depth image MB. The firstcompressed information may be a first image IPM representing an IPM ofthe first image MB or a first image MV representing an MV of the firstimage MB.

Then, the 3D image encoding apparatus 100 generates second compressedinformation using the first compressed information in operation 914.Here, the second image MB is another one of the color image MB and thedepth image MB which is different from the first image MB. The secondcompressed information may be a second image IPM representing an IPM ofthe second image MB or a second image MV representing an MV of thesecond image MB.

The 3D image encoding apparatus 100 encodes the first image MB using thefirst compressed information in operation 916. The 3D image encodingapparatus 100 encodes the second image MB using the second compressedinformation in operation 918. The 3D image encoding apparatus 100transmits the encoded first image MB and the encoded second image MB tothe 3D image decoding apparatus 150 in operation 920.

When the compressed information is an IPM, a process of generating thefirst image IPM and the second image IPM is described below withreference to FIGS. 10 to 12.

FIG. 10 is a flowchart illustrating a process of generating an IPM of acolor image or a depth image according to example embodiments.

Referring to FIG. 10, the first compressed information generation unit112 generates prediction blocks based on IPMs from boundary pixels toadjacent blocks to the first image MB in operation 1010.

The first compressed information generation unit 112 differentiates thefirst image MB by the prediction blocks and rate-distortion optimizesthe a differentiation result to examine a compression efficiency inoperation 1020.

Then, the first compressed information generation unit 112 determines anIPM having relatively high or best compression efficiency among the IPMsas the first image IPM in operation 1030.

FIG. 11 is a flowchart illustrating an example of generating an IPM ofan image using an IPM of another image according to example embodiments.

Referring to FIG. 11, the second compressed information generation unit122 receives the first image IPM in operation 1110. Then, the secondcompressed information generation unit 122 determines the first imageIPM as the second image IPM that is an IPM of the second image MB inoperation 1120.

FIG. 12 is a flowchart illustrating another example of generating an IPMof an image using an IPM of another image according to exampleembodiments.

Referring to FIG. 12, the second compressed information generation unit122 receives the first image IPM in operation 1210. Then, the secondcompressed information generation unit 122 generates candidate IPMsusing the first image IPM in operation 1220. Here, the candidate IPMsare generated by tilting the first image IPM at a preset angle to theright or left. Here, a weighted value of the boundary pixels of theadjacent blocks may vary based on the preset angle.

The second compressed information generation unit 122 generatescandidate prediction blocks according to the candidate IPMs fromboundary pixels to adjacent pixels to the second image MB in operation1230.

The second compressed information generation unit 122 differentiates thesecond image MB by the candidate prediction blocks and rate-distortionoptimizes a differentiation result to examine a compression efficiencyin operation 1240.

The second compressed information generation unit 122 determines acandidate IPM corresponding to a prediction block having superior orrelatively high compression efficiency as the second image IPM inoperation 1250.

When the compressed information is an MV, a process of generating thefirst image MV and the second image MV will be described below withreference to FIGS. 13 to 16.

FIG. 13 is a flowchart illustrating a process of generating a motionvector of a color image or a depth image according to exampleembodiments.

Referring to FIG. 13, the first compressed information generation unit112 calculates the first image PMV using the first image MB and theadjacent blocks in operation 1310. Here, the first image PMV is a vectorobtained by median filter of MVs of left, upper, and upper-right blocksthat are the first image MB and the adjacent blocks inhorizontal/vertical directions, respectively.

The first compressed information generation unit 112 explores the firstimage MV that is a final MV of the first image MB by motion explorationin a first image based on the first image PMV in operation 1320.

FIG. 14 is a flowchart illustrating an example of generating an MV of animage using an MV of another image according to example embodiments.

Referring to FIG. 14, the second compressed information generation unit122 receives the first image MV in operation 1410. Then, the secondcompressed information generation unit 122 determines the first image MVas the second image MV representing an MV of the second image MB inoperation 1420.

FIG. 15 is a flowchart illustrating another example of generating an MVof an image using an MV of another image according to exampleembodiments.

Referring to FIG. 15, the second compressed information generation unit122 receives the first image MV in operation 1510. The second compressedinformation generation unit 122 determines the first image MV as asecond image PMV in operation 1520. The second compressed informationgeneration unit 122 generates the second image MV that is a final MV ofthe second image MB by motion exploration in a second image based on thesecond image PMV in operation 1530.

FIG. 16 is a flowchart illustrating still another example of generatingan MV of an image using an MV of another image according to exampleembodiments.

Referring to FIG. 16, the second compressed information generation unit122 receives the first image MV in operation 1610. The second compressedinformation generation unit 122 determines the first image MV as asecond image first PMV in operation 1620.

The second compressed information generation unit 122 generates a secondimage first MV that is a candidate MV of the second image MB by motionexploration in the second image based on the second image first PMV inoperation 1630.

The second compressed information generation unit 122 calculates asecond image second PMV using the second image MB and the adjacentblocks in operation 1640.

The second compressed information generation unit 122 generates a secondimage second MV that is an MV of the second image MB by motionexploration in the second image based on the second image second PMV inoperation 1650.

The second compressed information generation unit 122 selects an MVhaving a minimum motion cost function as the second image MV bycomparing the second image first MV with the second image second MV.

As described above, there are provided a 3D image encoding apparatus andmethod which generate first compressed information used to encode oneimage of two types of images forming a 3D image, and generate secondcompressed information used to encode another one image using the firstcompressed information. Since the two images are substantiallyassociated with each other, one image refers to compressed informationof the other image to have a relatively higher compression efficiency.

Although a few embodiments have been shown and described, it would beappreciated by those skilled in the art that changes may be made inthese embodiments without departing from the principles and spirit ofthe disclosure, the scope of which is defined by the claims and theirequivalents.

1. A three-dimensional (3D) image encoding apparatus, the apparatuscomprising: a first encoder to generate first compressed information ina first image macroblock (MB) which is one of images to form a 3D image,and to encode the first image MB using the first compressed information;and a second encoder to generate second compressed information using thefirst compressed information, and to encode a second image MB which isanother one of the images to form the 3D image using the secondcompressed information.
 2. The apparatus of claim 1, wherein the firstimage MB is one of a color image MB and a depth image MB, and the secondimage MB is another one of the color image MB and the depth image MBwhich is different from the first image MB.
 3. The apparatus of claim 1,wherein the first compressed information is a first image intraprediction mode (IPM) which represents an IPM of the first image MB, andthe second compressed information is a second image IPM to represent anIPM of the second image MB.
 4. The apparatus of claim 3, wherein thefirst encoder comprises a first image intra prediction unit torespectively generate prediction blocks according to IPMs; and a firstimage IPM determination unit to examine a compression efficiency bydifferentiating the first image MB by the prediction blocks andrate-distortion optimizing a differentiation result and to determine anIPM having superior or relatively high compression efficiency among theIPMs as the first image IPM.
 5. The apparatus of claim 3, wherein thesecond encoder comprises a second image IPM determination unit todetermine the first image IPM as the second image IPM that is the IPM ofthe second image MB.
 6. The apparatus of claim 3, wherein the secondencoder comprises: a candidate IPM generation unit to generate candidateIPMs using the first image IPM; a second image intra prediction unit torespectively generate candidate prediction blocks according to thecandidate IPMs and the second image MB; and a second image IPMdetermination unit to examine a compression efficiency bydifferentiating the second image MB by the candidate prediction blocksand rate-distortion optimizing a differentiation result, and todetermine a candidate IPM having superior or relatively high compressionefficiency among the candidate IPMs as the second image IPM.
 7. Theapparatus of claim 1, wherein the first compressed information is afirst image motion vector (MV) to represent an MV of the first image MB,and the second compressed information is a second image MV to representan MV of the second image MB.
 8. The apparatus of claim 7, wherein thefirst encoder comprises a first image predictive MV (PMV) calculationunit to calculate a first image PMV which represents a PMV of the firstimage MB using the first image MB and adjacent blocks; and a first imagemotion explorer to generate the first image MV that is a final MV of thefirst image MB by motion exploration in a first image based on the firstimage PMV.
 9. The apparatus of claim 7, wherein the second encodercomprises a second image MV determination unit to determine the firstimage MV as the second image MV that is a final MV of the second imageMB.
 10. The apparatus of claim 7, wherein the second encoder comprises asecond image motion explorer to generate the second image MV that is afinal MV of the second image MB by motion exploration in a second imagebased on the first image MV.
 11. The apparatus of claim 7, wherein thesecond encoder comprises: a second image first motion explorer togenerate a second image first MV which is one of candidate MVs of thesecond image MB by motion exploration in a second image based on thefirst image MV; a second image PMV calculation unit to calculate asecond image PMV which represents a PMV of the second image MB using thesecond image MB block and adjacent blocks; a motion explorer to generatea second image second MV which is one of the candidate MVs of the secondimage MB by motion exploration in the second image based on the secondimage PMV; and a second image MV selection unit to select an MV having aminimum or relatively low motion cost function as the second image MV bycomparing the second image first MV with the second image second MV. 12.A 3D image decoding apparatus, the apparatus comprising: a first decoderto decode an encoded first image MB using first compressed informationwhen receiving the encoded first image MB which is one of images to forma 3D image and the first compressed information; and a second decoder togenerate second compressed information using the first compressedinformation and to decode an encoded second image MB using the secondcompressed information when receiving the encoded second image MB whichis another one of the images to form the 3D image.
 13. The apparatus ofclaim 12, wherein the first image MB is one of a color image MB and adepth image MB, and the second image MB is another one of the colorimage MB and the depth image MB which is different from the first imageMB.
 14. The apparatus of claim 12, wherein the first compressedinformation is a first image IPM to represent an IPM of the first imageMB, and the second compressed information is a second image IPM torepresent an IPM of the second image MB.
 15. The apparatus of claim 14,wherein the first decoder receives the first image IPM along with theencoded first image MB and decodes the encoded first image MB using thefirst image IPM.
 16. The apparatus of claim 14, wherein the seconddecoder receives the encoded second image MB and decodes the encodedsecond image MB using the first image IPM.
 17. The apparatus of claim14, wherein the second decoder receives an index bit along with theencoded second image MB, generates candidate IPMs using the first imageIPM, and decodes the encoded second image MB using a candidate IPMcorresponding to the index bit among the candidate IPMs as the secondimage IPM.
 18. The apparatus of claim 12, wherein the first compressedinformation is a first image MV which represents an MV of the firstimage MB, and the second compressed information is a second image MVwhich represents an MV of the second image MB.
 19. The apparatus ofclaim 18, wherein the first decoder receives the first image MV alongwith the encoded first image MB and decodes the encoded first image MBusing the first image MV.
 20. The apparatus of claim 18, wherein thesecond decoder receives the encoded second image MB and decodes theencoded second image MB using the first image MV.
 21. The apparatus ofclaim 18, wherein the second decoder receives the encoded second imageMB, reconstructs the second image MV using the first image MV as asecond image PMV, and decodes the encoded second image MB using thesecond image MV.
 22. The apparatus of claim 18, wherein the seconddecoder receives the encoded second image MB and an index bit; and thesecond decoder reconstructs the second image MV using the first image MVas a second image PMV and decodes the encoded second image MB using thesecond image MV when either the index bit indicates the first image MVis the second image PMV, or the second decoder decodes the encodedsecond image MB using the second image MV received along with theencoded second image MB when the index bit indicates that the second PMVis calculated through the second image MB.
 23. A 3D image encodingmethod, the method comprising: generating first compressed informationin a first image MB which is one of images to form a 3D image andencoding the first image MB using the first compressed information; andgenerating second compressed information using the first compressedinformation and encoding a second image MB which is another one of theimages to form the 3D image using the second compressed information. 24.The method of claim 23, wherein the first image MB is one of a colorimage MB and a depth image MB, and the second image MB is another one ofthe color image MB and the depth image which is different from the firstimage MB.
 25. The method of claim 23, wherein the first compressedinformation is a first image IPM to represent an IPM of the first imageMB, and the second compressed information is a second image IPM torepresent an IPM of the second image MB.
 26. The method of claim 25,wherein the generating of the first compressed information comprises:respectively generating prediction blocks according to IPMs; examining acompression efficiency by differentiating the first image MB by theprediction blocks and rate-distortion optimizing the first image MB; anddetermining an IPM having superior compression efficiency among the IPMsas the first image IPM.
 27. The method of claim 25, wherein thegenerating of the second compressed information comprises determiningthe first image IPM as the second image IPM that is an IPM of the secondimage MB.
 28. The method of claim 25, wherein the generating of thesecond compressed information comprises: generating candidate IPMs usingthe first image IPM; respectively generating candidate prediction blocksaccording to the candidate IPMs; examining a compression efficiency bydifferentiating the second image MB by the candidate prediction blocksand rate-distortion optimizing the second image MB; and determining acandidate IPM having superior or relatively high compression efficiencyamong the candidate IPMs as the second image IPM.
 29. The method ofclaim 23, wherein the first compressed information is a first image MVwhich represents an MV of the first image MB, and the second compressedinformation is a second image MV which represents an MV of the secondimage MB.
 30. The method of claim 29, wherein the generating of thefirst image PMV that is the first compressed information comprises:calculating the first image PMV which represents a PMV of the firstimage MB using the first image MB and adjacent blocks; and generatingthe first image MV that is a final MV of the first image MB by motionexploration of a first image.
 31. The method of claim 29, wherein thegenerating of the second image PMV that is the second compressedinformation comprises determining the first image MV as the second imageMV that is a final MV of the second image MB.
 32. The method of claim29, wherein the generating of the second image PMV that is the secondcompressed information comprises generating the second image MV that isa final MV of the second image MB by motion exploration of a secondimage based on the first image MV.
 33. The method of claim 25, whereinthe generating of the second image PMV that is the second compressedinformation comprises generating a second image first MV which is one ofcandidate MVs of the second image MB by motion exploration of a secondimage based on the first image MV; calculating a second image PMV whichrepresents a PMV of the second image MB using the second image MB andadjacent blocks; generating a second image second MV which is one of thecandidate MVs of the second image MB by motion exploration of the secondimage based on the second PMV; and selecting an MV having a minimum orrelatively low motion cost function as the second image MV by comparingthe second image first MV and the second image second MV.
 34. A 3D imagedecoding method, the method comprising: receiving an encoded first imageMB which is one of images to form a 3D image and a first compressedinformation; decoding the encoded first image MB using the firstcompressed image; receiving an encoded second image MB which is anotherone of the images to form the 3D image; generating second compressedinformation using the first compressed information; and decoding theencoded second image MB using the second compressed information.